Globoid cell leukodystrophy (GLD; Krabbe's Disease) is a fatal inherited disease that affects kittens, puppies and children. It results from a deficiency of the enzyme galactosylceramidase which results in progressive degeneration of brain and spinal white matter and neuropathy. The pathogenesis by which the enzymatic deficiency leads to degeneration is not well understood, and our research is directed toward increased understanding of the pathogenesis. Our current goals are: 1) to describe the compositional difference between white matter that is highly susceptible to degeneration in contrast to white matter that is relatively resistant to degeneration, to gain insight into resistance to the disease process; 2) to document the pattern of lesion distribution in brain and spinal cord, to analyze consistency of the disease process and correlate lesion intensity and rate with enzymatic activity level; 3) to identify the pathogenic role of Schwann cells and distinguish whether they initiate myelin loss or merely autophagocytize myelin after it has begun to disintegrate.